Optical semiconductor package and method for manufacturing the same

ABSTRACT

A semiconductor package includes an interconnect structure having a first surface and a second surface opposite to the first surface, at least one optical chip over the first surface of the interconnect structure and electrically coupled to the interconnect structure, an insulating layer contacting the second surface of the interconnect structure, and a molding compound over the first surface of the interconnect structure. The insulating layer includes a third surface facing the second surface of the interconnect structure and a fourth surface opposite to the third surface. At least an edge of the optical chip is covered by the molding compound.

BACKGROUND

The demands of advanced electronic technology require electronicproducts to be made lighter, thinner, faster and smarter whilesimultaneously making them more friendly, powerful, reliable, robust andless expensive. Therefore, the trend for electronic packages is todevelop highly-integrated packaging structures. The multi-chip module(MCM) package can integrate the chips having different functions, suchas microprocessors, memories, logic elements, optical ICs andcapacitors, and replaces the prior art of disposing individual packageson one circuit board. Therefore, the packaging size is decreased and thereliability of the memory device is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a flow chart representing a method for manufacturing asemiconductor package in accordance with some embodiments of the presentdisclosure.

FIG. 2 is a flow chart representing a method for manufacturing asemiconductor package in accordance with some embodiments of the presentdisclosure.

FIG. 3 is a flow chart representing a method for manufacturing asemiconductor package in accordance with some embodiments of the presentdisclosure.

FIGS. 4A through 4M illustrate sectional views of a semiconductorpackage at various fabrication stages constructed according to aspectsof the present disclosure in one or more embodiments.

FIG. 5 is a sectional view of a semiconductor package according to otheraspects of the present disclosure in some embodiments.

FIGS. 6A through 6B illustrate sectional views of a semiconductorpackage at various fabrication stages constructed according to aspectsof the present disclosure in one or more embodiments.

FIG. 7 is a sectional view of a semiconductor package according to otheraspects of the present disclosure in some embodiments.

FIG. 8 is a sectional view of a semiconductor package according to otheraspects of the present disclosure in some embodiments.

FIGS. 9A through 9G illustrate sectional views of a semiconductorpackage at various fabrication stages constructed according to aspectsof the present disclosure in one or more embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of elements and arrangements are describedbelow to simplify the present disclosure, These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper”, “on” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

As used herein, the terms such as “first”, “second” and “third” describevarious elements, components, regions, layers and/or sections, theseelements, components, regions, layers and/or sections should not belimited by these terms. These terms may be only used to distinguish oneelement, component, region, layer or section from another. The termssuch as “first”, “second” and “third” when used herein do not imply asequence or order unless clearly indicated by the context.

As used herein, the terms “approximately,” “substantially,”“substantial” and “about” are used to describe and account for smallvariations. When used in conjunction with an event or circumstance, theterms can refer to instances in which the event or circumstance occursprecisely as well as instances in which the event or circumstance occursto a close approximation. For example, when used in conjunction with anumerical value, the terms can refer to a range of variation of lessthan or equal to ±10% of that numerical value, such as less than orequal to ±5%, less than or equal to ±4%, less than or equal to ±3%, lessthan or equal to ±2%, less than or equal to ±1%, less than or equal to±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. Forexample, two numerical values can be deemed to be “substantially” thesame or equal if a difference between the values is less than or equalto ±10% of an average of the values, such as less than or equal to ±5%,less than or equal to ±4%, less than or equal to ±3%, less than or equalto ±2%, less than or equal to ±1%, less than or equal to ±0.5%, lessthan or equal to ±0.1%, or less than or equal to ±0.05%. For example,“substantially” parallel can refer to a range of angular variationrelative to 0° that is less than or equal to ±10°, such as less than orequal to ±5°, less than or equal to ±4°, less than or equal to ±3°, lessthan or equal to ±2°, less than or equal to ±1°, less than or equal to±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°. Forexample, “substantially” perpendicular can refer to a range of angularvariation relative to 90° that is less than or equal to ±10°, such asless than or equal to ±5°, less than or equal to ±4°, less than or equalto ±3°, less than or equal to ±2°, less than or equal to ±1°, less thanor equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to±0.05°.

Other features and processes may also be included. For example, testingstructures may be included to aid in the verification testing of the 3Dpackaging or 3DIC devices. The testing structures may include, forexample, test pads formed in a redistribution layer or on a substratethat allows the testing of the 3D packaging or 3DIC, the use of probesand/or probe cards, and the like. The verification testing may beperformed on intermediate structures as well as the final structure.Additionally, the structures and methods disclosed herein may be used inconjunction with testing methodologies that incorporate intermediateverification of known good dies to increase the yield and decreasecosts.

In one embodiment, a silicon photonic transceiver includesoptoelectronic transceivers and optical source that enable communicationof optical signals vertically to and from the surface of a photonicbench, which usually includes an interconnection structure, a siliconinterposer, and through-substrate vias (referred to herein as TSVs)formed in the interposer. As known in the art, TSVs, which are alsocommonly referred to as through-silicon vias in the case of siliconsubstrates/wafer, are vertical electrical connections that extend thefull thickness of the bulk silicon interposer from one side to another.However, the silicon interposer including TSVs suffers high cost andlower throughput because fabricating the interposer with TSVs is acomplex process. Furthermore, the silicon photonic transceiver sufferselectric loss due to the long TSV signal path. Additionally, opticalloss exists as light prone to propagate into hulk silicon at the bottomof interposer.

Furthermore, it is found that the optical elements such as Laser chips,couplers and fibers are all mounted on the molding compound of thepackage. Thus, a silicon spacer embedded in the molding compound therebyallowing lights passing through is required. Consequently, the packagemay suffer from the increased optical path due to this arrangement. Moreimportantly, the photonic package is not a flat package, which is lesssuitable for subsequent manufacturing operations.

One or more implementations of the present disclosure will now bedescribed with reference to the attached drawings, wherein likereference numerals are used to refer to like elements throughout, andwherein the illustrated structures are not necessarily drawn to scale.As used herein, the terms “die” and “chip” are interchangeablethroughout the specification.

The terms “wafer” and “substrate” used herein include any structurehaving an exposed surface onto which a layer is deposited according tothe present invention, for example, to form the circuit structure suchas a redistribution layer (RDL). The term substrate is understood toinclude semiconductor wafers, but not limited thereto. The termsubstrate is also used to refer to semiconductor structures duringprocessing, and may include other layers that have been fabricatedthereupon.

The term “patterning” or “patterned” is used in the present disclosureto describe an operation of forming a predetermined pattern on asurface. The patterning operation includes various steps and processesand varies in accordance with the features of embodiments. In someembodiments, a patterning operation is adopted to pattern an existingfilm or layer. The patterning operation includes forming a mask on theexisting film or layer and removing the unmasked film or layer with anetch or other removal process. The mask is a photo resist, or a hardmask. In some embodiments, a patterning operation is adopted to form apatterned layer directly on a surface. The patterning operation includesforming a photosensitive film on the surface, conducting aphotolithography process and a developing process. The remainingphotosensitive film is retained and integrated into the semiconductordevice.

FIG. 1 is a flow chart representing a method for manufacturing asemiconductor package 10 in accordance with some embodiments of thepresent disclosure. The method for manufacturing the semiconductorpackage 10 includes an Operation 102: Providing a substrate including afirst side and a second side opposite to the first side, the substrateincluding at least one insulating layer at the first side, and aninterconnect structure being formed over the insulating layer, anOperation 104: Thinning the substrate from the second side, an Operation106: Disposing at least one optical chip over interconnect structure, anOperation 108: Disposing a molding compound over the interconnectstructure, and an Operation 110: Forming a plurality of conductivelayers over the substrate at the second side, wherein the conductivelayers are electrically coupled to the interconnect structure. Themethod for manufacturing the semiconductor package 10 will be furtherdescribed according to one or more embodiments. FIG. 2 is a flow chartrepresenting a method for manufacturing a semiconductor package 11 inaccordance with some embodiments of the present disclosure. The methodfor manufacturing the semiconductor package 11 includes an Operation112: Providing a substrate including a first side and a second sideopposite to the first side, the substrate including at least oneinsulating layer at the first side, and an interconnect structure beingformed over the insulating layer, an Operation 114: Thinning thesubstrate from the second side, an Operation 116: Disposing a moldingcompound over the interconnect structure, an Operation 118: Forming aplurality of conductive layers over the substrate at the second side,the conductive layers are electrically coupled to the interconnectstructure, and an Operation 120: Disposing at least one optical chipover the substrate at the second side. The method for forming thesemiconductor package 11 will be further described according to one ormore embodiments.

FIG. 3 is a flow chart representing a method for manufacturing asemiconductor package 20 in accordance with some embodiments of thepresent disclosure. The method for manufacturing the semiconductorpackage 20 includes an Operation 202: Providing a substrate including afirst side and a second side opposite to the first side, the substrateincluding at least one insulating layer at the first side, and aninterconnect structure being formed over the insulating layer, anOperation 204: Disposing at least one optical chip over interconnectstructure, an Operation 206: Disposing a molding compound over theinterconnect structure, an Operation 208: Thinning the substrate fromthe second side, and an Operation 210: Forming a plurality of conductivelayers over the substrate at the second side, the conductive layers areelectrically coupled to the interconnect structure. The method formanufacturing the semiconductor package 20 will be further describedaccording to one or more embodiments.

FIGS. 4A through 4M illustrate sectional views of a semiconductorpackage 30 at various fabrication stages constructed according toaspects of the present disclosure in some embodiments.

Referring to FIG. 4A, a substrate 300 is provided according to Operation102. The substrate 300 includes a first side 300 a and a second side 300b opposite to the first side 300 a. In some embodiments of the presentdisclosure, the substrate 300 may include a silicon substrate althoughother semiconductor substrates, such as silicon-germanium substrate orcompound substrate may be utilized in various embodiments. In someembodiments of the present disclosure, the substrate 300 includes asilicon on insulator (SOI) substrate. In some embodiments of the presentdisclosure, the substrate 300 includes a semiconductor layer 306 formedon an insulator layer 304 at the first side 300 a, and the semiconductorlayer 306 can include, for example but not limited to, silicon. Theinsulator layer 304 may be, for example, a buried oxide (BOX) layer or asilicon oxide layer. The insulator layer 304 is provided on a bulkstructure 302, typically a silicon or glass substrate. Other substances,such as multi-layered or gradient substrates may also be used. In someembodiments of the present disclosure, various operations can beperformed to form optical devices such as modulators, waveguide,detector, gratings, and/or couplers in the semiconductor layer 306.Therefore, the semiconductor layer 306 can be referred to as an opticaldevice layer 306. In other words, the optical device layer 306 includesmodulator, waveguide, detector, grating or coupler. In some embodimentsof the present disclosure, devices other than the optical devices can beformed if required. Additionally, a dielectric layer 308 includinginsulating material(s) can be formed over insulator layer 304 to provideprotection and form a planar surface for following operations.

Still referring to FIG. 4A, an interconnect structure 320 is formed overthe substrate 300 at the first side 300 a. Therefore, the optical devicelayer 306 is sandwiched between the least one insulator layer 304 andthe interconnect structure 320. The interconnect structure 320 includesa first surface 320 a and a second surface 320 b opposite to the firstsurface 320 a, and the second surface 320 b of the interconnectstructure 320 faces the substrate 300 and the dielectric layer 308 inthe optical device layer 306. The interconnect structure 320 can includeone or more redistribution layers (RDLs), and the RDL can include alayer of a dielectric layer 322 having conductive lines 324 formedtherein. The RDLs may be formed in a back-end-of-line (BEOL) process,but is not limited thereto. The dielectric layer 322 can include, forexample but not limited to, a polymer material, such as epoxy,polyimide, polybenzoxazole (PBO), and the like, or can be formed ofcommonly known dielectric materials, such as spin-on glass, siliconoxide (SiO), silicon oxynitride (SiON), or the like, formed by anysuitable method such as spin coating. The conductive lines 324 caninclude a metal such as copper (Cu), silver (Ag), aluminum (Al), nickel(Ni), combination thereof, or the like. The interconnect structure 320can be electrically coupled to the optical devices or other devices inthe optical device layer 306.

Referring to FIG. 4B and FIG. 4C, the substrate 300 and the interconnectstructure 320 are then flipped over and attached to a carrier substrate330 at the first side 300 a through an adhesive material 331, such as atape, a die attach film (DAF), or the like. Thereafter, the substrate300 is thinned from the second side 300 b according to Operation 104.Generally, the thinning can be, for example but not limited to, anetching, a grinding, or a planarization operation (e.g., chemicalmechanical polishing (CMP)). In some embodiments of the presentdisclosure, the bulk structure 302 of the substrate 300 is removed bythinning the substrate 300 from the second side 300 b. In someembodiments of the present disclosure, the hulk structure 302 may beremained on the substrate 300 at the second side 300 b, and the remainedbulk structure 302 (as shown in FIG. 8) includes a thickness less thanabout 50 micrometers (μm). In some embodiments, the dielectric layer 308and the thinned substrate including the insulator layer 304 and thesemiconductor layer 306 with or without the bulk structure 302 arereferred to as an insulating layer 310 contacting the second surface 320b, and the insulating layer 310 includes a thickness less than about 50μm. As shown in FIG. 4C, the insulating layer 310 includes a thirdsurface 310 a facing the second surface 320 b of the interconnectstructure 320 and a fourth surface 310 b opposite to the third surface310 a.

Referring to FIG. 4D, the insulating layer 310 and the interconnectstructure 320 are then detached from the carrier substrate 330 andattached to another carrier substrate 332 at the second side 300 bthrough another adhesive material 333, such as a tape, a DAF, or thelike, and followed by removing the carrier substrate 330 and theadhesive material 331. As shown in FIG. 4D, at least one optical chip340 is disposed over the first surface 320 a of the interconnectstructure 320 according to Operation 106. In some embodiments of thepresent disclosure, the optical chip 340 can include an assembly with anoptical source such as, for example but not limited to, a semiconductorlaser or a light-emitting diode. The optical chip 340 is electricallycoupled to the interconnect structure 320 through conductive structures342. In addition, the conductive structures 342 may be encapsulated withan underfill 344 for protection. In some embodiments, the conductivestructure 342 includes a microbump having a bump height lower than 10μm, for example, from 3 to 5 μm. The underfill material 344 can include,for example but not limited to, optical epoxy. Furthermore, a spacer 350is affixed to the first surface 320 a of the interconnect structure 320through an optical glue. The spacer 350 is transparent to anelectromagnetic wave of a predetermined wavelength range. In someembodiments of the present disclosure, the spacer 350 can includesilicon or glass, but not limited to this. Additionally, a protectinglayer 352 can formed over a top surface of the spacer 350 forprotection. In some embodiments of the present disclosure, theprotecting layer 352 can include a DAF, but not limited to this.

Still referring to FIG. 4D, in some embodiments of the presentdisclosure, a device chip 360 is disposed over the first surface 320 aof the interconnect structure 320. The device chip 360 can be anelectronic integrated circuit (EIC) chip. In some embodiments of thepresent disclosure, the device chip 360 can provide the requiredelectronic functions of the semiconductor package 30. The device chip360 is electrically coupled to the interconnect structure 320 throughconductive structures 362. In addition, the conductive structures 362may be encapsulated with an underfill 364 for protection.

Referring to FIG. 4E, a molding compound 370 is disposed over the firstsurface 320 a of the interconnect structure 320 according to Operation108. As shown in FIG. 4E, the optical chip 340, the spacer 350 and thedevice chip 360 are molded in the molding compound 370. The moldingcompound 370 can be a single layer film or a composite stack. Themolding compound 370 is applied to protect the optical chip 340, thespacer 350 and the device chip 360 and to provide mechanical stiffnessand enhance the mechanical strength of the semiconductor package 30. Themolding compound 370 may include any suitable material such as an epoxyresin, a molding underfill, or the like. Suitable methods for formingmolding compound 370 may include compressive molding, transfer molding,liquid encapsulant molding, or the like, For example, molding compound370 which may be dispensed between the chips 340/360 and the spacer 350in liquid form. Subsequently, a curing process is performed to solidifymolding compound 370. The filling of molding compound 370 may overflowover the chips 340/360 and the spacer 350 so that molding compound 370covers top surfaces of the chips 340/360 and the spacer 350. In someembodiments of the present disclosure, a thinning operation is thereforeperformed to expose at least a top surface of the protecting layer 352.Such thinning operation may employ a mechanical grinding process, achemical polishing process, an etching process, combination thereof, orthe like. Consequently, at least an edge of the optical chip 340 iscovered by the molding compound 370.

Referring to FIGS. 4F and FIG. 4G, the semiconductor package 30 is thenflipped over, detached from the carrier substrate 332, and attached toanother carrier substrate 334 at the first side 300 a through anadhesive material 335, such as a tape, a DAF, or the like, and followedby removing the carrier substrate 332 and the adhesive material 333.Subsequently, a photoresist 336 is formed on the insulating layer 310 atthe second side 300 b. As shown in FIG. 4G, the photoresist 336 is thenpatterned to define locations of external terminals, which will bedescribed. Subsequently, the insulating layer 310 (including theinsulator 304, the optical device layer 306 and the dielectric layer308) is patterned to expose portions of the interconnect structure 320at the second surface 320 b.

Referring to FIG. 4H and FIG. 4I, the patterned photoresist 336 isremoved and followed by conformally forming a polymer layer 380 to coverthe insulating layer 310 and the exposed portions of the interconnectstructure 320. The polymer layer 380 includes a polymeric material suchas epoxy, polyimide, polybenzoxazole (PBO), solder resist (SR), ABFfilm, and the like. Another photoresist 337 is formed on polymer layer380 and patterned. Subsequently, the polymer layer 380 is patterned toexpose portions of the interconnect structure 320 at the second surface320 b. In some embodiments, operations shown in FIG. 4H to FIG. 4I areoptional.

Referring to FIGS. 4J and 4K, the patterned photoresist 337 is thenremoved and followed by forming a conductive material 382 overinsulating layer 310, the polymer layer 380, and the exposed portions ofthe interconnect structure 320. The conductive material 382 can be made,for example but not limited to, by physical vapor deposition (PVD), CVD,electrical plating, electroless plating, or any combinations thereof. Insome embodiments, the process of forming the conductive material 382 caninclude an electroless nickel immersion gold (ENIG) process or animmersion tin (Im-Sn) process for forming ENIG or Im-Sn material on thesurface of the conductive material 382. In some embodiments of thepresent disclosure, the conductive material 382 can include a diffusionbarrier layer and a seed layer (not shown). The diffusion barrier layermay also function as an adhesion layer (or a glue layer), in someembodiments. The diffusion barrier layer may be formed of tantalumnitride (TaN), although it may also be formed of other materials such astitanium nitride (TiN), tantalum (Ta), titanium (Ti), or the like. Theseed layer may be a Cu seed layer formed on the diffusion harrier layer.The Cu seed layer may be formed of Cu or one of Cu alloys that includeAg, Ni, chromium (Cr), tin (Sn), gold (Au), and combinations thereof.Thereafter, another photoresist 338 is formed on the conductive material382 as shown in FIG. 4J, and the photoresists 338 is patterned as shownin FIG. 4K. Next, portions of the conductive material 382 are removedwith the patterned photoresist 338 serving as a mask. Accordingly, aplurality of conductive layers 384 is formed over the substrate at thesecond side 300 b according to Operation 110. In other words, theconductive layers 384 are formed over the fourth surface 310 b of theinsulating layer 310. The conductive layers 384 serve asunder-hump-metallurgy (UBM) layers. As shown in FIG. 4K, the conductivelayers 384 are electrically coupled to the interconnect structure 320.

As shown in FIG. 4K, because the thickness of the insulating layer 310is less than 50 μm, the conductive layers 384 are able to provide thevertical electric connections from the first side 300 a to the secondside 300 b of the insulating layer 310. In other words, TSVs thatconventionally used to provide vertical electrical connections arereplaced with the conductive layers 384.

Referring to FIGS. 4L and 4M, the patterned photoresist 338 is removed.A plurality of external terminals 386 is formed in contact with theconductive layers 384. The external terminals 386 can include solderballs, metal pads, metal pillars, and/or combination thereof, and may beformed of Au, Ag, Ni, Al, tungsten (W), and/or alloys thereof. Theadhesive material 335 and the carrier substrate 334 are then removed,and the semiconductor package 30 is flipped over. As shown in FIG. 4M,the protecting layer 352 over the top surface of the spacer 350 isremoved and an optical fiber or other external optical coupling device356 is affixed to the top surface of the spacer 350 through, for examplebut not limited to, an optical glue. The optical fiber 356 is configuredto transmit the electromagnetic wave of the predetermined wavelengthrange.

As shown in FIG. 4M, the optical chip 340 is disposed on theinterconnect structure 320 and the insulating layer 310. Since thethickness of the insulating layer 310 (including the dielectric layer308, the optical device 306 and the insulator layer 304) with or withoutthe bulk structure is reduced to 50 μm or below, electrical path lengththrough vertical electric connections in the insulating layer 310 isshortened. Accordingly, electrical loss is reduced. Additionally, thesubstrate 300 is thinned enough such that the conductive layer 384 canserve as a mirror. In some embodiments of the present disclosure, theoptical path of emission of optical chip 340 projectively overlaps theconductive layers 384, such that light can be reflected by theconductive layers 384. Accordingly, optical loss can be further reducedand optical coupling efficiency can be improved. In some embodiments ofthe present disclosure, the substrate 300 is thinned down to that onlyentire or partial insulating layer 310 is remained on the second side300 b of substrate 300, which also reduces optical loss caused byoptical guiding within bulk structure 302.

FIG. 5 is a sectional view of a semiconductor package 32 according toaspects of the present disclosure in some embodiments. Accordingly,similar features in FIGS. 4A-4M and 5 are identified by the samereference numerals for clarity and simplicity. The method formanufacturing the semiconductor package 10 can be performed to form thesemiconductor package 32 and those details are omitted in the interestof brevity. As shown in FIG. 5, in me embodiments of the disclosure, theoptical fiber or other external optical coupling device 356 is affixedto lateral surfaces of the interconnect structure 320 and the insulatinglayer 310 through an optical glue. And at least one edge coupler 358 isformed in the optical device layer 306 in the insulating layer 310adjacent to the optical fiber or other external optical coupling device356.

According to the abovementioned embodiment, the optical chip 340 ismolded in the molding compound 370, the flatness of the semiconductorpackage 30 and 32 is therefore improved.

FIGS. 6A through 6B illustrate sectional views of a semiconductorpackage 40 at various fabrication stages constructed according toaspects of the present disclosure in some embodiments.

Referring to FIG. 6A-6B, it should be understood that similar featuresin FIGS. 4A-4M and 6A-6B may include the similar materials, thus thosedetails are omitted in the interest of brevity. And the method forforming the semiconductor package 11 can be performed to form thesemiconductor package 40. Referring to FIG. 6A, a substrate (not shown)is provided according to Operation 112. The substrate includes a firstside 400 a and a second side 400 b opposite to the first side 400 a. Insome embodiments of the present disclosure, the substrate may include aSOI substrate. In some embodiments of the present disclosure, thesubstrate 400 may include a semiconductor layer 406 formed on aninsulator layer 404 at the first side 400 a, and the insulator layer 404is provided on a bulk structure 402 (as shown in FIG. 8). In someembodiments of the present disclosure, various operations can beperformed to form optical devices such as modulators, waveguide,detector, gratings, and/or couplers in the semiconductor layer 406.Therefore, the semiconductor layer 406 can be referred to as an opticaldevice layer 406. In other words, the optical device layer 406 includesmodulator, waveguide, detector, grating or coupler, In some embodimentsof the present disclosure, devices other than the optical devices can beformed if required. Additionally, a dielectric layer 408 can be formedon the insulator layer 404 to provide protection and form a planarsurface for following operations.

Still referring to FIG. 6A, an interconnect structure 420 is formed overthe substrate at the first side 400 a. Therefore, the optical devicelayer 406 is sandwiched between the least. one insulator layer 404 andthe interconnect structure 420. The interconnect structure 420 includesa first surface 420 a and a second surface 420 b opposite to the firstsurface 420 a, and the second surface 420 b of the interconnectstructure 420 faces the substrate and the dielectric layer 408 in theoptical device layer 406. The interconnect structure 420 can include oneor more redistribution layers (RDLs), and the RDL can include a layer ofa dielectric layer 422 having conductive lines 424 formed therein. Asmentioned above, the RDLs may be formed in a back-end-of-line (BEOL)process, but is not limited thereto.

Still referring to FIG. 6A, the substrate and the interconnect structure420 are then flipped over and attached to a carrier substrate (notshown) at the first side 400 a through an adhesive material (not shown).Thereafter, the substrate is thinned from the second side 400 baccording to Operation 114. In some embodiments of the presentdisclosure, the bulk structure of the substrate is removed by thinningthe substrate from the second side 400 b. In some embodiments of thepresent disclosure, the bulk structure may be remained on the substrateat the second side 400 b, and the remained bulk structure 402 (as shownin FIG. 8) includes a thickness less than about 50 μm. In someembodiments other words, the dielectric layer 408 and the thinnedsubstrate including the insulator layer 404 and the semiconductor layer406 with or without the bulk structure are referred to as an insulatinglayer 410, and the insulating layer 410 includes a thickness less thanabout 50 μm. As shown in FIG. 6A, the insulating layer 410 includes athird surface 410 a facing the second surface 420 b of the interconnectstructure 420 and a fourth surface 410 b opposite to the third surface410 a.

Still referring to FIG. 6A, the insulating layer 410 and theinterconnect structure 420 are then attached to another carriersubstrate (not shown) at the second side by another adhesive material(not shown). And the above mentioned carrier substrate and adhesivematerial are removed from the first side 400 a of the substrate. Asshown in FIG. 6A, at least. one device chip 460 is disposed over thefirst surface 420 a of the interconnect structure 420. The device chip460 can be an electronic integrated circuit (EIC) chip. In someembodiments of the present disclosure, the device chip 460 can providethe required electronic functions of the semiconductor package 40. Thedevice chip 460 is electrically coupled to the interconnect structure420 through conductive structures 462. In addition, the conductivestructures 462 may be encapsulated with an underfill 464 for protection.

Still referring to FIG. 6A, a molding compound 470 is disposed over thefirst surface 420 a of the interconnect structure 420 according toOperation 116. As shown in FIG. 6A, the device chip 460 is molded in themolding compound 470. Subsequently, the semiconductor package 40 is thenflipped over and attached to another carrier substrate (not shown) atthe first side 400 a through an adhesive material (not shown). Next, theinsulating layer 410 (including the insulator 404, the optical devicelayer 406 and the dielectric layer 408) is patterned to expose portionsof the interconnect structure 420 at the second surface 420 b. A polymerlayer 480 is then conformally formed to cover the insulating layer 410and the exposed portions of the interconnect structure 420.Subsequently, the polymer layer 480 is patterned to expose portions ofthe interconnect structure 420 at the second surface 420 b.

Still referring to FIG. 6A, a conductive material is formed over thepolymer 480 and followed by patterning. Consequently, a plurality ofconductive layers 484 is formed over the substrate at the second side400 b according to Operation 118. In other words, the conductive layers484 are formed over the fourth surface 410 b of the insulating layer410. The conductive layers 484 serve as UBM layers. A plurality ofexternal terminals 486 is then formed in contact with the conductivelayers 484.

As mentioned above, because the thickness of the insulating layer 410 isless than 50 μm, the conductive layers 484 are able to provide thevertical electric connections from the first side 400 a to the secondside 400 b of the insulating layer 410. In other words, TSVs thatconventionally used to provide vertical electrical connections arereplaced with the conductive layers 484.

Referring to FIG. 6B, an optical chip 440 is then disposed over thesubstrate at the second side 400 b according to Operation 120. In otherwords, the optical chip 440 is disposed over the fourth surface 410 b ofthe insulating layer 410. The optical chip 440 is electrically coupledto the interconnect structure 420 through the conductive layer 484 asshown in FIG. 6B. Furthermore, the optical chip 440 can be affixed tothe substrate through an underfill material 444. As shown in FIG. 6B, insome embodiments of the disclosure, an optical fiber or other externaloptical coupling device 456 is affixed to lateral surfaces of theinterconnect structure 420 and the insulating layer 410 through anoptical glue (not shown). And at least one edge coupler 458 is formed inthe optical device layer 406 in the insulating layer 410 adjacent to theoptical fiber 456.

FIG. 7 is a sectional view of a semiconductor package 42 according toaspects of the present disclosure in some embodiments. Accordingly,similar features in FIGS. 6A-6B and 7 are identified by the samereference numerals for clarity and simplicity. The method formanufacturing the semiconductor package 11 can be performed to form thesemiconductor package 42. As shown in FIG. 7, in some embodiments of thedisclosure, a spacer 450 is affixed to the first surface 420 a of theinterconnect structure 420 through an optical glue before performingOperation 116. The spacer 450 is transparent to an electromagnetic waveof a predetermined wavelength range. In some embodiments of the presentdisclosure, the spacer 450 can include silicon or glass, but not limitedto this. And an optical fiber or other external optical coupling device456 is affixed to the top surface of the spacer 450 through, for examplebut not limited to, an optical glue after Operation 120. The opticalfiber or other external optical coupling device 456 is configured totransmit the electromagnetic wave of the predetermined wavelength range.Accordingly, optical coupling efficiency can be further improved.

FIG. 8 is a sectional view of a semiconductor package 44 according toaspects of the present disclosure in some embodiments. Accordingly,similar features in FIGS. 6A-6B and 8 are identified by the samereference numerals for clarity and simplicity. The method formanufacturing the semiconductor package 11 can be performed to form thesemiconductor package 44. As shown in FIG. 8, in some embodiments of thedisclosure, the bulk structure 402 can be remained on the substrate 400at the second side 400 b, and the remained bulk structure 402 includes athickness less than about 50 μm.

According to the abovementioned embodiments, the optical chip 440 isdisposed at the second side 400 b while the device chip 460 is at thefirst side 400 b. In other words, the optical chip 440 and the devicechip 460 are disposed at opposite sides of the semiconductor package40/42/44. As shown in FIGS. 6A through 8, though the optical chip 440 isnot molded in the molding compound 470, the optical chip 440 is disposedat the second side 400 b where the conductive layers 484 and theexternal terminals 486 are disposed, therefore flatness of thesemiconductor package 40/42/44 is still improved.

FIGS. 9A through 9G illustrate sectional views of a semiconductorpackage 50 at various fabrication stages constructed according toaspects of the present disclosure in some embodiments. It should beunderstood that similar features in FIGS. 4A-4M and 9A-9G may includethe similar materials, thus those details are omitted in the interest ofbrevity. The method for manufacturing the semiconductor package 20 canbe performed to form the semiconductor package 50 and those details areomitted in the interest of brevity.

Referring to FIG. 9A, a substrate 500 is provided according to Operation202. The substrate 500 includes a first side 500 a and a second side 500b opposite to the first side 500 a. In some embodiments of the presentdisclosure, the substrate 500 includes a semiconductor layer 506 formedon an insulator layer 504 at the first side 500 a. The insulator layer504 is provided on a bulk structure 502, typically a silicon or glasssubstrate. Other substances, such as multi-layered or gradientsubstrates may also be used. In some embodiments of the presentdisclosure, various operations can be performed to form optical devicessuch as modulators, waveguide, detector, gratings, and/or couplers inthe semiconductor layer 506. Therefore, the semiconductor layer 506 canbe referred to as an optical device layer 506. In other words, theoptical device layer 506 includes modulator, waveguide, detector,grating or coupler. In some embodiments of the present disclosure,devices other than the optical devices can be formed if required.Additionally, a dielectric layer 508 including insulating material(s)can be formed over insulator layer 504 to provide protection and form aplanar surface for following operations, in some embodiments, aplurality of openings 512 can be formed in the insulating layer 508, thesemiconductor layer 506, the insulator layer 504, and the bulk structure502, as shown in FIG. 9A.

Referring to FIG. 9B, a plurality of connectors 514 is formed in theopenings 512. In some embodiments, the connectors 514 fill the openings512, but the disclosure is not limited thereto. Referring to FIG. 9C, aninterconnect structure 520 is formed over the substrate 500 at the firstside 500 a according to operation 202. Therefore, the optical devicelayer 506 is sandwiched between the least one insulator layer 504 andthe interconnect structure 520. The interconnect structure 520 includesa first surface 520 a and a second surface 520 b opposite to the firstsurface 520 a, and the second surface 520 b of the interconnectstructure 520 faces the substrate 500 and the dielectric layer 508 inthe optical device layer 506. The interconnect structure 520 can includeone or more RDLs, and the RDL can include a layer of a dielectric layer522 having conductive lines 524 formed therein. The interconnectstructure 520 can be electrically coupled to the optical devices orother devices in the optical device layer 506. In some embodiments, theinterconnect structure 520 is electrically coupled to the connectors514.

Referring to FIG. 9D, at least one optical chip 540 is disposed over thefirst surface 520 a of the interconnect structure 520 according toOperation 204, in some embodiments of the present disclosure, theoptical chip 540 can include an assembly with an optical source such as,for example but not limited to, a semiconductor laser or alight-emitting diode. The optical chip 540 is electrically coupled tothe interconnect structure 520 through conductive structures 542. Inaddition, the conductive structures 542 may be encapsulated with anunderfill 544 for protection. Furthermore, a spacer 550 is affixed tothe first surface 520 a of the interconnect structure 520 through anoptical glue. The spacer 550 is transparent to an electromagnetic waveof a predetermined wavelength range. Additionally, a protecting layer552 can formed over a top surface of the spacer 550 for protection. Insome embodiments of the present disclosure, the protecting layer 552 caninclude a DAF, but not limited to this. In some embodiments of thepresent disclosure, a device chip 560 is disposed over the first surface520 a of the interconnect structure 520. The device chip 560 can be anelectronic integrated circuit (EIC) chip. In some embodiments of thepresent disclosure, the device chip 560 can provide the requiredelectronic functions of the semiconductor package 50. The device chip560 is electrically coupled to the interconnect structure 520 throughconductive structures 562. In addition, the conductive structures 562may be encapsulated with an underfill 564 for protection.

Still referring to FIG. 9D, a molding compound 570 is disposed over thefirst surface 520 a of the interconnect structure 520 according toOperation 206. As shown in FIG. 9D, the optical chip 540, the spacer 550and the device chip 560 are molded in the molding compound 570. Themolding compound 570 can be a single layer film or a composite stack.The molding compound 570 is applied to protect the optical chip 540, thespacer 550 and the device chip 560 and to provide mechanical stiffnessand enhance the mechanical strength of the semiconductor package 50. Insome embodiments of the present, disclosure, at least an edge of theoptical chip 540 is covered by the molding compound 570.

Referring to FIG. 9E, the substrate 500 is then flipped over andattached to a carrier substrate 530 at the first side 500 a through anadhesive material 531. Thereafter, the substrate 500 is thinned from thesecond side 500 b to expose the connectors 514 according to Operation208. In some embodiments of the present disclosure, the bulk structure502 of the substrate 500 is removed by thinning the substrate 500 fromthe second side 500 b. In some embodiments of the present disclosure,the bulk structure 502 may be remained on the substrate 500 at thesecond side 500 b, and the remained bulk structure 502 includes athickness less than about 50 μm, as shown in FIG. 9E. In someembodiments, the dielectric layer 508 and the thinned substrate 500including the insulator layer 504 and the semiconductor layer 506 withor without the bulk structure 502 are referred to as an insulating layer510, and the insulating layer 510 includes a thickness less than about50 μm. As shown in FIG. 9E, the insulating layer 510 includes a thirdsurface 510 a facing the second surface 520 b of the interconnectstructure 520 and a fourth surface 510 b opposite to the third surface510 a.

Referring to FIG. 9F, a polymer layer 580 is formed to cover portions ofthe insulating layer 510 and the exposed connectors 514. Subsequently,the polymer layer 580 is patterned to expose the connectors 514 from thefourth surface 510 b. In some embodiments, operations shown in FIG. 9Fare optional. Next, a conductive material 582 is formed over insulatinglayer 510, the polymer layer 580, and the exposed connectors 514. Insome embodiments of the present disclosure, the conductive material 582can include a diffusion barrier layer and a seed layer (not shown).

Referring to FIG. 9G, another patterned photoresist (not shown) isformed on the conductive material 582. Next, portions of the conductivematerial 582 are removed with the patterned photoresist serving as amask. Accordingly, a plurality of conductive layers 584 is formed overthe substrate at the second side 500 b according to Operation 210. Inother words, the conductive layers 584 are formed over the fourthsurface 510 b of the insulating layer 510. The conductive layers 584serve as UBM layers. As shown in FIG. 9G, the conductive layers 584 areelectrically coupled to the interconnect structure 520 through theconnectors 514.

Still referring to FIG. 9G, the patterned photoresist is removed, and aplurality of external terminals 586 is formed in contact with theconductive layers 584. The external terminals 586 can include solderballs, metal pads, metal pillars, and/or combination thereof. Althoughnot shown, those skilled in the art would easily realize that theadhesive material 531 and the carrier substrate 530 are then removed,and the semiconductor package 50 is flipped over. Further, theprotecting layer 552 over the top surface of the spacer 550 is removedand an optical fiber or other external optical coupling device (notshown) can be affixed to the top surface of the spacer 550 through, forexample but not limited to, an optical glue. As mentioned above, theoptical fiber is configured to transmit the electromagnetic wave of thepredetermined wavelength range. Furthermore, those skilled in the artwould understand that in some embodiments, the optical fiber or otherexternal optical coupling device can be affixed to lateral surfaces ofthe interconnect structure 520 and the insulating layer 510 through anoptical glue as aforementioned and shown in FIG. 5. And at least oneedge coupler (not shown) is formed in the optical device layer 506 inthe insulating layer 510 adjacent to the optical fiber or other externaloptical coupling device as aforementioned and shown in FIG. 5.

According to the abovementioned embodiment, the optical chip 540 ismolded in the molding compound 570, the flatness of the semiconductorpackage 50 is therefore improved. In some embodiments, the remained bulkstructure 502 provides stronger mechanical strength. In someembodiments, the optical chip 540 can be disposed over the substrate 500at the second side 500 b. In other words, the optical chip 540 isdisposed over the fourth surface 510 b of the insulating layer 510. Inthose embodiments, the optical chip 540 is electrically coupled to theinterconnect structure 520 through conductive layer 584 and theconnectors 514.

In the present disclosure, the insulating layer (including the insulatorlayer, the optical device layer, and the dielectric layer) with orwithout the bulk structure serve as a TSV-less or a TSV-free structuresuch that the conductive layers are electrically coupled to theinterconnect structure without TSVs. That is, the conductive layersprovide vertical electric connections from the first side to the secondside of the insulating layer. Accordingly, routing path is shortened dueto elimination of the TSV signal path, which may be over 100 μm. Thus,electrical loss is reduced and electrical performance is improved. Themanufacturing method for forming the semiconductor package is thereforesimplified. More importantly, since the optical chip is molded withinthe molding compound or disposed at the side where the conductive layersand the external terminals are disposed, flatness of the semiconductorpackage is improved.

In some embodiments, a semiconductor package is provided. Thesemiconductor package includes an interconnect structure having a firstsurface and a second surface opposite to the first surface, at least oneoptical chip over the first surface of the interconnect structure andelectrically coupled to the interconnect structure, an insulating layercontacting the second surface of the interconnect structure, and amolding compound over the first surface of the interconnect structure.The insulating layer includes a third surface facing the second surfaceof the interconnect structure and a fourth surface opposite to the thirdsurface. At least an edge of the optical chip is covered by the moldingcompound.

In some embodiments, a semiconductor package is provided. Thesemiconductor package includes an interconnect structure having a firstsurface and a second surface opposite to the first surface, aninsulating layer contacting the second surface of the interconnectstructure wherein the insulating layer has a third surface facing thesecond surface of the interconnect structure and a fourth surfaceopposite to the third surface, at least one optical chip over the fourthsurface of the insulating layer and electrically coupled to theinterconnect structure, and a molding compound over the first surface ofthe interconnect structure.

In some embodiments, a method for manufacturing a semiconductor packageis provided. The method includes providing a substrate comprising afirst side and a second side opposite to the first side, the substratecomprising at least one insulating layer at the first side, and aninterconnect structure over the insulating layer; thinning the substratefrom the second side; disposing at least one optical chip over thesubstrate; disposing a molding compound over the interconnect structure;and forming a plurality of conductive layers over the substrate at thesecond side. The conductive layers are electrically coupled to theinterconnect structure.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

1. A semiconductor package comprising: an interconnect structure comprising a first surface and a second surface opposite to the first surface; at least one optical chip over the first surface of the interconnect structure and electrically coupled to the interconnect structure; an insulating layer contacting the second surface of the interconnect structure, wherein the insulating layer comprises a third surface facing the second surface of the interconnect structure and a fourth surface opposite to the third surface; a plurality of conductive layers extending from the third surface of the insulating layer to the fourth surface of the insulating layer and electrically coupled to the interconnect structure; and a molding compound over the first surface of the interconnect structure, wherein at least an edge of the optical chip is covered by the molding compound.
 2. The semiconductor package of claim 1, further comprising: at least one spacer over the first surface of the interconnect structure and covered by the molding compound; and at least one optical fiber configured to transmit electromagnetic wave of a predetermined wavelength range, the at least one optical fiber affixed to the spacer, wherein the spacer being transparent to the electromagnetic wave of the predetermined wavelength range.
 3. The semiconductor package of claim 2, wherein the spacer comprises a silicon spacer or a glass spacer.
 4. The semiconductor package of claim 1, further comprising: at least one optical fiber affixed to lateral surfaces of the interconnect structure and the insulating layer; and at least one edge coupler in the insulating layer and adjacent to the optical fiber.
 5. (canceled)
 6. The semiconductor package of claim 1, wherein the optical chip projectively overlaps at least a portion of the conductive layers.
 7. The semiconductor package of claim 1, further comprising a plurality of external terminals in contact with the conductive layers.
 8. The semiconductor package of claim 1, further comprising an optical device layer sandwiched between the interconnect structure and the insulating layer.
 9. The semiconductor package of claim 8, wherein the optical device layer comprises modulator, waveguide, detector, grating or coupler. 10-20. (canceled)
 21. A semiconductor package comprising: an interconnect structure comprising a first surface and a second surface opposite to the first surface; an insulating layer contacting the second surface of the interconnect structure, wherein the insulating layer comprises a third surface facing the second surface of the interconnect structure and a fourth surface opposite to the third surface; a conductive layer extending from the third surface of the insulating layer to the fourth surface of the insulating layer and electrically coupled to the interconnect structure, wherein the conductive layer covers a portion of the fourth surface of the insulating layer; a molding compound over the first surface of the interconnect structure; a spacer over the first surface of the interconnect structure and covered by the molding compound; and an optical fiber configured to transmit electromagnetic wave of a predetermined wavelength range, the optical fiber affixed to the spacer.
 22. The semiconductor package of claim 21, wherein the spacer being transparent to the electromagnetic wave of the predetermined wavelength range.
 23. The semiconductor package of claim 21, further comprising a first chip over the first surface of the interconnect structure and electrically coupled to the interconnect structure.
 24. The semiconductor package of claim 23, further comprising a second chip over the first surface of the interconnect structure and electrically coupled to the interconnect structure.
 25. The semiconductor package of claim 21, further comprising an optical device layer sandwiched between the interconnect structure and the insulating layer.
 26. The semiconductor package of claim 25, wherein the spacer is in contact with the optical device layer.
 27. The semiconductor package of claim 21, further comprising a plurality of external terminals at the fourth surface of the insulating layer.
 28. A semiconductor package comprising: an interconnect structure comprising a first surface and a second surface opposite to the first surface; an optical chip over the first surface of the interconnect structure and electrically coupled to the interconnect structure; an optical device layer over the second surface of the interconnect structure and electrically coupled to the interconnect structure; a conductive layer disposed over the second surface of the interconnect structure and separated from the optical device layer; and an optical fiber affixed to the first surface of the interconnect structure.
 29. The semiconductor package of claim 28, further comprising a spacer between the optical fiber and the first surface of the interconnect structure.
 30. The semiconductor package of claim 29, wherein the spacer is transparent to a predetermined wavelength range transmitting by the optical fiber.
 31. The semiconductor package of claim 28, further comprising an external terminal at the second surface of the interconnect structure, wherein the optical chip projectively overlaps the external terminal.
 32. The semiconductor package of claim 8, wherein the optical device layer is separate from the plurality conductive layers by the insulating layer. 